Over at Forbes, personal finance writer Casey Bond points out that airline rewards miles can be confusing because 25,000 miles doesn’t at all mean you’ll be able to score 25,000 free travel miles. Here’s how to get a ballpark idea of how much you’ve actually earned, according to your rewards:

The general rule of thumb for reward miles or any credit card rewards (such as points) is that they are worth $0.01 each,” explained Matthew Coan, owner of credit card comparison website Casavvy.com. ...Most cards that offer miles as their rewards make redeeming them for travel expenses your best option. So if you racked up 10,000 “miles” (or points) over the course of a year, you would essentially be able to redeem them towards $100 in travel expenses.

Again, it’s not an exact amount—if you’re looking for something more precise, try this tool—but it’s a decent rule for quickly figuring out how far your miles will take you. For more detail, head to the full post at the link below.